[INAUGURATION VIDEO]: TRUMP IS SWORN IN, VOWING TO REMAKE NATION

Donald John Trump was sworn in Friday as the nation’s 45th president and delivered a fiery nationalist manifesto that promised a populist restoration by stripping power from Washington’s elites and ending an era of “American carnage.”

Framing his ascension as transformational and global in its impact, Trump delivered a dark inaugural address in which he pledged fealty to all Americans. But he made little overt attempt to soothe a nation still wounded from arguably the ­ugliest election season of modern times and signaled that he intends to govern as if waging a permanent political campaign.

“I will fight for you with every breath in my body, and I will never, ever let you down,” Mr. Trump told hundreds of thousands of rain-soaked admirers and onlookers in a forceful 16-minute Inaugural Address from the West Front of the Capitol. “America will start winning again, winning like never before. We will bring back our jobs. We will bring back our borders. We will bring back our wealth. And we will bring back our dreams.”

Mr. Trump’s ascension amounted to a hostile takeover of a capital facing its most significant disruption in generations. While officially a Republican, he has taken on leaders of both parties and, with no prior political career of his own, made clear that he saw himself as the ultimate outsider not beholden to the current system. “We will no longer accept politicians who are all talk and no action, constantly complaining but never doing anything about it,” he said. “The time for empty talk is over. Now arrives the hour of action. Do not allow anyone to tell you that it cannot be done.”

Mr. Trump’s view of the United States was strikingly grim for an Inaugural Address — a country where mothers and children are “trapped in poverty in our inner cities,” where “rusted-out factories” are “scattered like tombstones across the landscape” and where drugs and crime “have stolen too many lives.”

“This American carnage,” he declared, “stops right here and stops right now.”

He got started right away with rolling back the policies of his predecessor, former President BarackObama, by issuing orders freezing new regulations from recent weeks and ordering agencies to “ease the burden” of the Affordable Care Act during the transition from repealing to replacing the law. More orders are planned for next week.

Wearing a dark suit and red tie and accompanied by his wife, Melania, in a powder-blue suit and matching gloves, Mr. Trump took the 35-word oath administered by Chief Justice John G. Roberts Jr. precisely at noon. Michael Richard Pence, a former governor and congressman from Indiana, was sworn in minutes before as vice president by Justice Clarence Thomas.

Mr. Trump assumed the presidency of a country still unsettled after a polarizing election and entered office with less support in polls than any other president in recent history. It was clear from the day that there would be no grace period either for or by the new president. The Senate confirmed two cabinet nominations — James N. Mattis as defense secretary and John F. Kelly as secretary of homeland security — but Democrats temporarily held up Mike Pompeo’s confirmation as C.I.A. director.

Throughout the day, there were mostly peaceful protests against the new president. Sporadic violence broke out as demonstrators smashed shop windows and burned a limousine, while police officers in riot helmets responded with tear gas. More than 200 people were arrested. Liberal groups prepared for a women’s march on Saturday that they said could draw hundreds of thousands.

Mr. Trump made only passing efforts to reach out to Democrats beyond thanking Mr. Obama and his wife, Michelle, for their handling of the transition. “They have been magnificent,” he said in his speech.

He later praised his defeated opponent, Hillary Clinton, at a lobster-and-beef luncheon with congressional leaders, asking her and former President Bill Clinton to stand for applause. “I have a lot of respect for these two people,” he said.